In the field of optical communications, a Tunable Laser (TL) is a laser whose output wavelength can be adjusted within a particular range. The tunable laser is mainly applied to optical transmission by means of coherent modulation, and coherent modulation has become a mainstream solution in the industry in long-distance optical transmission at a rate of 100 G and above. Driven by growing requirements on bandwidths, the market size continues to grow rapidly, and higher requirements are imposed on a tunable optical laser in terms of a size, costs, performance, reliability, and the like. A monolithically integrated tunable laser has such advantages as a small size and a high integration level, and therefore, has become a current mainstream technology in the field of optical communications.
A tunable laser may be substantially manufactured by connecting a gain area to a passive area on an Indium Phosphide (InP) substrate. The gain area is usually a Multiple Quantum Well (MQW), and the passive area mainly includes a reflector (for example, a Distributed Bragg Reflector (DBR)) section and a phase section. Wavelength tuning is implemented by tuning a refractive index of the DBR section. There are mainly two types of tuning mechanisms: tuning by means of current injection and thermal tuning using a local heating. Thermal tuning has a lower tuning loss than tuning by means of current injection, and therefore, implements a narrower line width of a laser, and can meet a requirement of a high-speed optical transmission network for a narrow line width of a laser. However, within a similar wavelength range, power consumption in a thermal tuning technology is much higher than power consumption in tuning by means of current injection.
In short, by means of the thermal tuning technology, a narrower line width of a laser can be obtained, and the requirement of the high-speed optical transmission network can be met. However, there is a problem that a tuning component has excessively high power consumption.